Non-woven product

ABSTRACT

A NON-WOVEN NYLON ARTICLE, PARTICULARLY USEFUL AS A CARPET BACKING FOR EITHER TUFTED AND/OR NEEDLE-PUNCHED CARPTES, IN ITS PREFERRED FORM COMPRISING A NON-WOVEN NYLON MAT AND AN OPEN FILAMENT YARN BASE BONDED BY A COMBINATION OF NEEDLE-PUNCHING AND SELECTIVE HEAT TREATMENT, AND A BINDER, AS DESCRIBED HEREINAFTER.

United States Patent 3,834,978 NON-WOVEN PRODUCT Stanley M. Nisenson andDavid L. Green, Brooklyn, N.Y., assignors to Allied ChemicalCorporation, New York,

No Drawing. Continuation of abandoned application Ser. No. 881,268, Dec.1, 1969. This application June 12, 1972, Ser. No. 261,770

Int. Cl. B32b 5/06 US. Cl. 161-81 2 Claims ABSTRACT OF THE DISCLOSUREThis is a continuation of application Ser. No. 881,268, filed Dec. 1,1969, now abandoned.

BACKGROUND AND PRIOR ART The field of non-Wovens i now replete withpublications on all aspects of product, product usage, and manufacture.The principles on which production of nonwovens is based are relativelysimple, but their application in practice is an extremely complex art,one in fact which has become highly developed in a relatively few years.The background and prior art publications relative to this inventiongenerally deal with disclosures concerning variations in web production,as by use of carding equipment, cross-laying or overlapping several weblayers thus formed, continuous filament lay-down on a moving conveyor,random deposition by the well known Rando- Webber machine, etc.Similarly, much is published concerning various bonding processes bychemical and/or heat means, binders, fillers, and other non-wovenmanipulations and components. A good summary of non-woven development isset out in The Development of Non- Wovvn Fabrics by A. R. Smith,Chemistry and Industry, Dec. 28, 1968, which includes some 77 referencesto articles and patents.

Previous publications of particular pertinence to the present inventionare US. Pat. 3,394,043, disclosing a non-woven polypropylene carpetbacking marketed under the trademark Locktuft and also US. Pat.3,286,007, disclosing a polypropylene non-woven carpet backing marketedunder the trademark Prime Bak. Polypropylene products of this type havebeen used considerably, due primarily to economic reasons and eventhough lacking certain physical property attributes due to the nature ofpolypropylene. For example, polypropylene, although relativelyinexpensive, is physically incapable of taking many of the moreinexpensive dyes and the commonly used cheaper lubricants; therefore, itis necessary to utilize polysiloxane or silicone base lubricants, andeven when these materials are used the lubricated web will not becompatible with a continuous dyebath operation and has a low receptivityfor most adhesives. Further, the polypropylene webs are incompatiblyheat sensitive with hot melt backing systems of today.

SUMMARY AND OBJECTS The present invention is concerned with improvingcarpet backings, particularly with respect to heat sensitivity,receptivity to adhesives, dyeing characteristics and to weight,strength, durability, and the like. This is accomplished by employingnylon in a novel combination of material and by combining the materialsin a particular, novel manner. More specifically, this invention pro-Patented Sept. 10, 1974 vides, for the time, a carpet backing comprisedentirely or almost entirely of nylon, but which is economical. The nylonbacking is much less heat sensitive and can therefore be tufted athigher needle speeds, will readily accept inexpensive lubricants such asalkylated fatty acids, will readily accept a wide range of adhesives,related soaps and/or surfactants, and has excellent dyeingcharacteristics as well as other advantages over previously known carpetbackings, with or without nylon included therein.

These objects and others are achieved primarily from a novel selectionof economic materials, which may include the use of garnetted nylonfibers to a certain extent, within certain appropriate size, weight, anddenier ranges. The materials are combined in a strong, yet light weightand flexible unit which itself affords advantages, and which has furtheradvantages in alleviating or solving problems of backing and carpetmanufacture inherent with prior art backings.

A principal object of the invention is, therefore, to provide a novelnon-woven carpet backing having a relatively low density and goodmechanical strength comprising a nylon web and an open filament yarnbase, :bonded by a combination of needle-punching and selective heating,and in the preferred embodiments further comprising a small amount ofsynthetic latex, acrylic or other binders.

Another object is to provide improved carpet backing articles comprisedin part of matrix filaments or fibers blended with the other substratematerials, matrix filaments or fibers referring to filamentary materialcontaining at least two different fiber forming polymeric materialshaving difi'ering melting points, the lower melting component thereofforming a matrix in which the other is dispersed in microfibrillar form.A further object is to provide a non-woven web for a carpet backing,comprised of nylon fibers blended with virgin staple fibers as will bedescribed.

Other objects and advantages will be described and will become apparentto those skilled in this art from the appended claims and followingdescription of the best mode of carrying out the invention, and examplesthereof.

DESCRIPTION In acoordance with the present invention, the product iscomposed of non-woven substrate comprised of nylon staple fibers havinga denier of 3 to 15 which is reinforced by either a parallel layer ofcontinuous filament nylon of to 200 denier or a woven scrim. Thenonwoven substrate may be needle-punched both before and after thereinforcement elements are added to the construction thereof. Thereinforced structure is consolidated by the combined processes ofneedle-punching and. heat setting under critically selected conditions.The heat setting may be accomplished by calendering and/or embossingbetween opposed pressure rolls or platens, or by other types of heatsources.

The preferred carpet backing of this invention is a non-Woven web or matproduced by random air laid staple fibers, or carded or garnetted andlapped web or webs to form a substrate. The substrate thus formed isneedle-punched into a parallel laid nylon filament scrim yarn interposedon one side of the substrate or between web layers thereof. It ispreferable to provide the latter construction although a single web onone side of the scrim will also produce a good product. Afterneedlepunch bonding together, the mat' and scrim are then heat treated,as by calendering on an embossing calender, or otherwise subjected topoint fusion, to further bond certain discrete areas while leaving alarge proportion of the fibers in a relatively free state. The mat andscrim product 3 7 thus produced has a finished weight of 2.5-4.5 ouncesper square yard, 3.2-4.0 preferably, which is considerably less weightthan the above-mentioned polypropylene backings. Finally, the product isstrengthened and stabilized with a small proportionate amount ofsynthetic adhesive by spray bonding, drying and heat setting undercontrolled conditions.

The nylon mat-nylon scrim combination and the combination of needlepunching and calendering result in a product which is relativelyinsensitive to heat (350 F.), as compared to the polypropylene backing(230 F.), and thus can be utilized with the new hot melt backingsystems. In dyeing operations the nylon backing readily accepts thecommonly used dyes and thereby avoids grinning problems frequentlyencountered with other natural or synthetic materials of differentcolors that resist dyes or takes on different shades than the tufting.Also, its heat sensitivity and porosity permits the backing to besubjected to faster and more uniform drying temperature while at thesame time air can pass through the web (after tufting or needling). And,in addition to the normal advantages of non-Wovens over the availableWovens, the carpet backing of this invention will not ravel at the edgesand will have a more dimensionally stabilized construction than eitheravailable Wovens or non-Wovens.

The low weight web material, being produced at high speeds of up toabout 30 feet per minute or more, for example, may be composed of staplefibers, or blends thereof, staple (fibers plus producer textured wasteyarns, or merely blends of producer textured waste yarns reprocessed bygarnetting. The nylon staple fibers should be within the range of 3-15denier, although it is preferred that a major portion be in the range of5 to 8. The preferred staple fiber length is from 2% to 4 /2 inches withthe higher denier staple being of longer length generally.

Tests have proven that the most critical factors involved in producingthe carpet backing of this invention reside in the appropriate selectionof denier and staple. Thus, the denier employed for the nylon web shouldbe such that at least 50 percent by weight of the web be of 5 to 8denier, and more specifically, in the following approximate ranges:

The reinforcing scrim may be woven or parallel laid nylon filament (inthe machine direction), preferably ranging from 90 to 120 denier, l endsper inch of width.

The following specific example of the preferred embodiment hereof isillustrative of the invention. Nylon 6 staple fiber of 2% inches length,'50 percent 15 denier per filament and 50 percent 6 denier per filamentwere blended and opened. A tendem weighing device was utilized tobalance out fiber weight for the web.

Webs produced by a carding machine were crosslapped at approximately 85to give a 2.5 ounce per square yard mat and a nylon scrim was insertedbetween upper and lower webs. Actually, in the preferred embodiment thescrim was a continuous yarn laid into the center of the material in themachine direction and weighed 0.15 ounce per square yard, a total of 100denier-10 ends per inch, giving a total mat and scrim weight of 2.65ounces per square yard. Upon completion of web laying and scriminsertion, the material is lightly compressed to reduce its loftiness.As an alternative of equal quality, a woven nylon scrim, weighingbetween. 0.12. and 0.35 ounce per square yard as, for example, by 5 or 6by 6 count, or 6- Warp by 2-3 fill, may be used.

To avoid setting up lines of stress in the final product it ispreferable to employ a random, non-uniform needle pattern. The mat fedthrough the needle loom under low tension was penetrated inch, 200punches per minute,

.4 needle 15 by 18 by 36 by 3 /2 round barb. The penetration count foreach of two passes was 200 per square inch.

The embossing is performed on both sides of the needled mat preferably,but not necessarily, by at least two different patterns. Suitablepatterns are, for example, pigskin, scroll, bubble, alligator and thelike. Thus a broad scroll pattern was used on the face or upper side ofthe mat to assure fusion and heat bonding on limited surface areas andwithin the mat, while the smaller pigskin pattern promoted surfacebonding only on the back side, the net result being an intermittentdiscontinuous bonding of the needled webs and scrim. A four rollcalender was used, with two pairs of steel engraved rolls runningagainst two firm fiber rolls. The embossed patterns will thereforeappear predominately on one side of the mat, and the other beingcomposed of freer fibers resulting in an article that can be very easilytufted, dyed and dried. The temperature range for calendering nylon 6(polycaproamide) is preferably about 400 to 420 F.; 410 Fri-4 F. (faceside) and 405F4 F. (back side) producing the best fusion bonding whileoperating at 400 to 700 pounds per square inch, preferably 600. Nylon6,6 (polyhexamethylene adipamide) requires temperatures approximately 45F. higher.

As a final bonding step, it is preferable to apply a limited amount ofadhesive synthetic binder (0.5 ounce per square yard). The latter isapplied by spray to the more highly bonded back side of the mat topreserve the advantages of the freer fiber side, yet contribute thebonding properties desired, i.e., the binder will penetrate into the matand promote dimensional stability and strength of the final product. Itis then dried in an infrared oven and cured in a festoon type airconnection oven at 350 F. for five minutes to completely cure the latex.The adhesive constituted 12 to 20 percent of the final product weight.

Immediately after the adhesive is applied to the heat fused mat, thelatter is passed through a heating zone (about F.) for about 45 secondsto drive off excess moisture and produce preliminary heat setting of theadhesive. Thereafter, the mat is exposed to the curing zone abovementioned. Next a lubricant spray is applied to reduce themetal-to-fiber friction during later carpet manufacturing proceduressuch as tufting and needlepunching. The lubricant constitutes anaddition of approximately 1 percent more weight to the carpet backing,and must be of a type compatible with the carpet dye bath. Lubricants ofthis type are known to the art.

As mentioned above, the advantages of the described non-woven carpetbacking are derived from its nylon composition and the manner in whichit is assembled. It is, of course, contemplated that minor amounts ofother synthetic or naturally occurring fiber and fiber-like materialscan be introduced into the web or scrim without departing from theessence of this invention. Similarly, additives such as alkalis or othersynthetic stabilizers, wetting agents, dispersing agents, antioxidants,plasticizers, pest repellents and the like may be added. Moreparticularly, as another embodiment of this invention the inclusion of asmall proportion (3 to 25 percent by weight) of a matrix staple fiber 2A to 4 inches long is contemplated and within approximately the samedenier ranges as given above, but preferably slightly higher, e.g., 5 to15.

As used herein, matrix-type fibers or filaments means filament made byinclusion of at least one polymeric material in the form ofdiscontinuous fibrils in a matrix of another, the two materials havingsubstantially different melt temperatures such that fibrousconstructions composed thereof can be bonded preferably, but notnecessarily, by application of heat below the melt temperature of oneand equal to or above that of the other, the entire filament compositionor any component thereof optionally mcluding y secondary materialcompatible with the bonding process and end utility of the product as awhole, such as antioxidants and other stabilizing agents, reinforcingparticles, fillers, adhesion promoting agents, fluorescent materials,dispersing agents, and others useful in polymerization, extruding,spinning, fabric forming and shaping, heat setting and product finishingtechniques. If desired, inorganic materials such as metal whiskers,fiberglas fibrils, asbestos particles and the like may be incorporatedfor conductive and/or reinforcement purposes.

The preferred matrix fibers useful herein are comprised of a homogeneousmixture of two different polymeric materials, the lower melting materialbeing nylon 6 and foming a matrix in which the higher melting material,preferably polyethylene terephthalate, is dispersed throughout in theform of discontinuous microfibers. Although various polymeric materialsare mixed together, they need not be entirely intermiscible due to theirphysical properties and/ or the mixing technique employed to dispersethe higher melting component in the matrix material for formingmicrofibers. Thus micro-sized globules or fibrils are usually initiallyproduced in the matrix, which when spun or drawn produce the desiredmicrofibrillar dispersion in the lower melting matrix material. As inthe case with any of the above-mentioned fibers, the component filamentsmay be round, trilobal, elliptical, or any other cross-sectional shape.

The principal advantage offered by employing matrixfilaments, whereinthe matrix is composed of a lower melting polymer than the dispersedcomponent, is their ability to bond by heating without flowing. Thus, anylon matrix fiber functions essentially as nylon fiber in the carpetbacking thereby contributing improved strength, tear and durability.

Matrix filaments have the ability to bond to each other, and to otherfilaments, in a manner which does not cause significant flow orcross-sectional disfiguration, thereby setting up conditions for bondingsystems that promote fiber orientation and strength and yet which admitcontrollable physical properties such as porosity, permeability,appearance, texture, etc.

Further, the matrix fibers effectively bond under the heat binderconditions preferred for this invention, such bonding being by localizedfusion partial or complete, of individual portions of the fibers. Suchfusion may be brought about by spark discharge through the web or theapplication of heat to highly localized, mechanically isolated portionsof the web as by embossing described above.

As to chemical make-up, the matrix filaments pertinent to this inventionare prepared from a polyester-polyamide combination. The compositionscontain 50 to 90 parts by weight nylon 6 and 50 to 10 parts by weight ofa polyester microfibrillar dispersion.

The following example is illustrative of the use of matrix fiber in thisinvention. The matrix filaments were produced in accordance with theformulation of Example 1 in US. Pat. 3,369,057, i.e., granularpolyethylene terephthalate polymer was used, melting about 255 C. (DTA)and about 265 C. (optical), having density (when amorphous) of about1.33 grams per cc. at 23 C. and about 1.38 grams per cc. in the form ofdrawn filament, having reduced viscosity of about 0.85 and having Tabout 65 C.

The polyester (30 parts) is mixed with 70 parts of granularpolycaproamide having reduced viscosity about 1.04, T about 35 C. anddensity about 1.14 grams per cc. at 23 C. Amine groups in thispolycaproamide had been blocked by reaction with sebacic acid, bringingthe amine group analyses thereof to 11 milliequivalents of NH2 groupsper kilogram of polymer, This polycaproamide contained as heatstabilizer 50 p.p.m. copper as cupric acetate.

The mixture of polyamide and polyester granules is blended in a doublecone blender for 1 hour. The granular blend is dried to a moisturecontent of no more than 0.01 percent; then melted at 285 C. in a 3 /2inch diameter screw extruder operated at a rotational speed of about 39r.p.m. to produce a pressure of 3,000 p.s.i.g. at the outlet. A drynitrogen atmosphere is used to protect the blend against absorbingmoisture. Residence time in the extruder was 8 minutes.

The molten mixture thereby obtained should have a melt viscosity ofabout approximately 2,000 poises at 285 C. The polyester will beuniformly distributed throughout and have average particle diameter ofabout 2 microns. The latter can be tested by cooling and solidifying asample of the melt, leaching out the polyamide component with formicacid and examining the residual polyester material.

The polymer blend thus produced is hereafter referred to by codedesignation as a nylon/polyester matrix fiber. The latter is formed intoa 10 denier fiber and cut into 3 /2 inch staple. A mixture of 20 percentby weight nylon/ polyester matrix fiber, percent nylon 6, 3 inch, 6denier staple was carded, deposited in cross-lapped webs to produce a3.0 ounce per square yard mat in the manner described above and combinedwith a 0.2 ounce per square yard parallel laid scrim. The mat scrim isthen fed through a needle loom under low tension, again in the mannerdescribed above. Thereafter, embossing is carried out by calenderingwith a broad scroll pattern on the upper surface and a pigskin patternon the bottomsurface, at slightly higher temperatures than with onlynylon, i.e., at 410 F. to 430 F., preferably 422 F. The matrix fiberbeing present in a significant amount, up to 25 percent, and the higherembossing, will result in point fusion of the matrix material, settingup a relatively firm, dimensionally stable network of fibers bonded toeach other and to the companion nylon fibers and scrim within the mat.

After the needle-punch and embossing steps synthetic latex is applied byspraying the bottom side and the backing dried and cured, all in themanner described above.

In another embodiment a 5 x 5 nylon scrim is used, interposed betweenlayers of a mat comprised of 8 percent nylon/polyester matrix fiberstaple 10 denier 3 inches long, and 92 percent nylon 6, 3 inches long, 6denier, the mat being 2.8 ounces per square yard and the scrim being 0.2ounce per square yard. All other process conditions and materials beingdescribed above.

We claim:

1. A synthetic carpet backing suitable for use in tufted and needlepunched carpets, comprising a sandwich of:

(a) first and second nonwoven webs formed from nylon staple, said nylonstaple having a staple length of from 2% to 4 /2 inches and a denierdistribution as follows:

(h) yarn base interposed between said first and second webs, andcomprising a machine direction continuously laid down layer of nylonmonofilament ranging from -260 denier and 5 to 15 ends per inch;

(c) said webs being randomly, nonuniformly needle punched, and fusionheat bonded primarily on the outer surface of both webs andintermittently on limited areas of said first web within said backing toproduce an intermittent discontinuous bonding of the needled webs andbase;

(d) said backing containing an additional 12-20 weight percent adhesivesynthetic binder only on said first web to preserve the advantage of thefreer fibers of said second web.

2.. A synthetic carpet backing suitable for use in tufted and needlepunched carpets, comprising a sandwich of:

Denier 7 Percentage (b) yarn base interposed between said first andsecond webs, and comprising a woven nylon scrim weighing between 0.12and 0.35 ounce per square yard;

' (c) said Webs being randomly, nonuniformly needle punched, and fusionheat bonded primarily on the outer surfaces of both webs andintermittently on limited areas of said first web within said backing toproduce an intermittent discontinuous bonding of the n'eedled webs andbase; (d) said backing containing an additional 12-20 weight percentadhesive synthetic binder only on said first Web to preserve theadvantages of the freer fibers of said second web.

References Cited UNITED STATES PATENTS Parlin et al. 161154 Isgur et al.156148 Smith 161154 Twilley 260857 Smith 161154 Sissons 161154 Sands156148 HAROLD ANSHER, Primary Examiner I. I. BELL, Assistant ExaminerU.S. C1. X.R.

Eggg I UNITED STATES PATENT OF'IFIICE CERTIFICATE. OF CORRECTION PatentNo. 3,834,978 Dated September 10, 1974 Invehmfls) Stanley M. Nlsensonand Davltl L. Green It is certified that error ap'pears in theabove-identified patent and that said Letters Patent are-herebycorrected as shown below:

Column 7, line 8; under heading "Percentage", "58-100" should read--50-l00- Signed and sealed this 17th day of December 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. c. MARSHALL DANN Commissioner of Patents AttestingOfficer

